test: function stored in a variable

Author: ada4a

clippy_lints/src/needless_path_new.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
-use clippy_utils::path_res;
 use clippy_utils::source::snippet;
+use clippy_utils::{expr_or_init, path_res};
 use rustc_errors::Applicability;
 use rustc_hir::def::{CtorKind, DefKind, Res};
 use rustc_hir::{Expr, ExprKind, QPath};
@@ -59,7 +59,9 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessPathNew {
         let (fn_did, args) = match e.kind {
             ExprKind::Call(callee, args)
                 if let Res::Def(DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(_, CtorKind::Fn), did) =
-                    path_res(cx, callee) =>
+                    // re: `expr_or_init`: `callee` might be a variable storing a fn ptr, for example,
+                    // so we need to get to the actual initializer
+                    path_res(cx, expr_or_init(cx, callee)) =>
             {
                 (did, args)
             },

tests/ui/needless_path_new.fixed

@@ -5,6 +5,8 @@ use std::path::Path;
 
 fn takes_path(_: &Path) {}
 
+fn takes_impl_path(_: impl AsRef<Path>) {}
+
 fn takes_path_and_impl_path(_: &Path, _: impl AsRef<Path>) {}
 
 fn takes_two_impl_paths_with_the_same_generic<P: AsRef<Path>>(_: P, _: P) {}
@@ -42,6 +44,10 @@ fn main() {
         "bar", //~ needless_path_new
     );
 
+    let a = takes_impl_path;
+
+    a("foo.txt"); //~ needless_path_new
+
     // no warning
     takes_path(Path::new("foo"));
 

tests/ui/needless_path_new.rs

@@ -5,6 +5,8 @@ use std::path::Path;
 
 fn takes_path(_: &Path) {}
 
+fn takes_impl_path(_: impl AsRef<Path>) {}
+
 fn takes_path_and_impl_path(_: &Path, _: impl AsRef<Path>) {}
 
 fn takes_two_impl_paths_with_the_same_generic<P: AsRef<Path>>(_: P, _: P) {}
@@ -42,6 +44,10 @@ fn main() {
         Path::new("bar"), //~ needless_path_new
     );
 
+    let a = takes_impl_path;
+
+    a(Path::new("foo.txt")); //~ needless_path_new
+
     // no warning
     takes_path(Path::new("foo"));
 

tests/ui/needless_path_new.stderr

@@ -7,20 +7,26 @@ LL |     fs::write(Path::new("foo.txt"), "foo");
    = note: `-D clippy::needless-path-new` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::needless_path_new)]`
 
+error: the expression enclosed in `Path::new` implements `AsRef<Path>`
+  --> tests/ui/needless_path_new.rs:31:9
+   |
+LL |         Path::new("bar"),
+   |         ^^^^^^^^^^^^^^^^ help: remove the enclosing `Path::new`: `"bar"`
+
 error: the expression enclosed in `Path::new` implements `AsRef<Path>`
   --> tests/ui/needless_path_new.rs:30:9
    |
 LL |         Path::new("foo"),
    |         ^^^^^^^^^^^^^^^^ help: remove the enclosing `Path::new`: `"foo"`
 
 error: the expression enclosed in `Path::new` implements `AsRef<Path>`
-  --> tests/ui/needless_path_new.rs:31:9
+  --> tests/ui/needless_path_new.rs:38:9
    |
 LL |         Path::new("bar"),
    |         ^^^^^^^^^^^^^^^^ help: remove the enclosing `Path::new`: `"bar"`
 
 error: the expression enclosed in `Path::new` implements `AsRef<Path>`
-  --> tests/ui/needless_path_new.rs:38:9
+  --> tests/ui/needless_path_new.rs:44:9
    |
 LL |         Path::new("bar"),
    |         ^^^^^^^^^^^^^^^^ help: remove the enclosing `Path::new`: `"bar"`
@@ -32,10 +38,10 @@ LL |         Path::new("foo"),
    |         ^^^^^^^^^^^^^^^^ help: remove the enclosing `Path::new`: `"foo"`
 
 error: the expression enclosed in `Path::new` implements `AsRef<Path>`
-  --> tests/ui/needless_path_new.rs:44:9
+  --> tests/ui/needless_path_new.rs:49:7
    |
-LL |         Path::new("bar"),
-   |         ^^^^^^^^^^^^^^^^ help: remove the enclosing `Path::new`: `"bar"`
+LL |     a(Path::new("foo.txt"));
+   |       ^^^^^^^^^^^^^^^^^^^^ help: remove the enclosing `Path::new`: `"foo.txt"`
 
-error: aborting due to 6 previous errors
+error: aborting due to 7 previous errors